Operating costs for the TSA unit
According to Figure 1, operating costs involves electrical energies in blowers to boost pressure of streams from ambient pressure to 2bar-g (during the adsorption, steam evacuation and cooling stages) and flow rate of steam consumed during heating stage. Electrical energy required for all blowers are calculated using the Aspen HYSYS process simulator by implementing equations 23-25. This electrical energy (kJ/h) is then converted to “kW.h” by considering duration of adsorption, steam evacuation and cooling stages. The electrical energy cost per each cycle is computed as $ 0.1 per “kW.h”. 23
Eq. (23)
The volume exponent is calculated as:
Eq. (24)
The correction factor is calculated as:
Eq. (25)
The amount of steam consuming in the heating stage at the pressure of 2bar-g is converted to “tone” by considering duration of heating stage. The price of low pressure steam is calculated by considering $ 13 per “tone” of steam. 23
Figure 7 clearly shows that the cost of using steam and electrical energies are 65% and 35% of total operating costs per each TSA cycle, in average. Hence, cost of steam has a great impact on total operating costs comparing to electrical energy.